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9x9 go
Normally, go is played on a 19x19 board.
However, other sizes occur sporadically,
and especially 9x9 is somewhat popular.
(Statistics: one can maybe collect 100000 Japanese pro games on 19x19
and perhaps 1000 Japanese pro games on 9x9. This site has
50000+ 19x19 games, and 500+ 9x9 games played by Japanese pros.)
Minigo
A long weekly series of 9x9 games came from the weekly
Yomiuri TV broadcast known as Minigo
(ミニ碁一番勝負).
Ricoh Pairgo
For Rico Pairgo
there is an intermediate round played on 9x9.
(Two rounds are played. The pairs who lost twice are out.
The pairs who won twice can continue. The pairs who won once
and lost once play an intermediate knockout round on 9x9.)
This yields 28 games for 2003-2009.
NHK
Some NHK special events
are played on 9x9.
Miscellaneous
Miscellaneous 9x9 events.
13x13 go
In 2014 a Pro 13x13 Tournament
was held.
Four 2015 Kansai Ki-in 13x13
2-game matches.
In 2016 a ProAma 13x13 Tournament
was held.
15x15 go
In 1964 a 15x15 game
Otake Hideo vs. Rin Kaiho was played.
17x17 go
In 2019 the Golaxy program played 17 tianyi games
on a 17x17 board and won 16-1.
21x21 go
In 1975 a 21x21 game
Hashimoto Shoji vs. Rin Kaiho was played.